During prosthesis surgery, severe hypotension, cardiovascular collapse, cardiac arrest and reduction in arterial oxygen tension are potential hazards which continue to give rise to concern whenever methylmethacrylate (MM) is implanted into bone. The exact mechanism(s) responsible for these adverse effects is (are) still unknown. In order to clarify the systemic effects of MM and to provide proper therapy whenever needed, further studies are required. The objectives of our study are: 1) to investigate the effects of MM on the pulmonary vasculature as modified by a) pharmacologically induced hypotension using pentolinium, trimethaphan or sodium nitroprusside, b) nitrous oxide and/or halothane anesthesia; 2) to investigate the hemodynamic effects of MM; 3) to identify the patients at risk and study their responses to implanted cement; 4) to define the anesthetic sequence or technique which is 'safest' for the patient who is to undergo prothesis surgery; and 5) to provide recommendations for the prevention of unwanted effects. This will require measurement of cardiac output, heart rate, central venous pressure, pulmonary artery pressure. Blood gas studies will also be done. Studies will be done before and after cement insertion and with nitrous oxide and/or halothane anesthesia.